Seed row Tolerance of 16-20-0-13 and 12-40-0-6.5S-1Zn in Western Canada


29 Apr 2016

2015 Annual Interpretive Summary

The majority of P-based fertilizers are either applied directly in the seed furrow (seed row) or side-banded close to the seed row, for the growing of small grain cereals and canola, in the Western Prairie provinces of Canada. Farmers using ammonium phosphate-sulfate (16-20-0-13S) fertilizer have reported that they can safely apply greater rates of phosphate in the form of 16-20-0-13S in the seed row, compared to regular monoammonium phosphate (11-52-0). To determine if this is accurate, a research study assessing the effect of low and elevated application rates of 16-20-0-13S placed in the seed rows of both spring wheat and canola was arranged with a regional applied research association (Wheatland Conservation Area Inc) out of Swift Current, Saskatchewan. The experimental design was a randomized complete block experiment with 13 treatments, replicated four times. The P treatments ranged from a low rate of 20 lb P2O5/A in 5 lb increments up to 40 lb/A. There were treatments using 11-52-0 and Rock 40 (12-40-0-6.5S-1Zn) at selected P rates, the same as some of the 16-20-0-13S treatments, for comparison. The crop year 2015 was the first of a planned two-year study.

2015 was very dry after planting in early May, at the Swift Current site. No significant amounts of precipitation were received until later June. However for assessing potential adverse effects of seed row-applied fertilizer this was probably useful. The high rate of 16-20-0-13S at 40 lb P2O5/A did decrease plant emergence counts for spring wheat by 27%, three weeks after planting, compared to lower rates of P application with some of the other forms of P fertilizer. However, the spring wheat compensated for the slightly lower plant stands and at harvest there was no significant difference between low, medium, or high rates of P application. For the canola, a smaller-seeded crop that is more sensitive to seed row-applied fertilizer, the high rates of 16-20-0-13S (30, 35, and 40 lb P2O5/A) decreased stands of emerged canola seedlings by up to 47%, compared to a 20 lb/A rate of 11-52-0 fertilizer. However, since canola is a so called "plastic crop" it is able to compensate in growth by increasing stem branching to produce as much yield as the 20 lb P2O5/A rate of 11-52-0 fertilizer.

One more year of research will help to better determine whether or not seed row-applied 16-20-0-13S is less prone to reduce spring wheat and canola emergence and yield compared to 11-52-0.